Forming electronic structures having dual dielectric thicknesses and the structure so formed

ABSTRACT

A structure including a first device and a second device, wherein the second device has a dielectric thickness greater than the dielectric thickness of the first device, and the method of so forming the structure.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to semiconductor devices, andmore particularly, to a method of forming semiconductor devices havingdual dielectric thicknesses, and the devices so formed.

2. Related Art

Currently, semiconductor devices are being constructed that are capableof performing several different functions, each potentially operating atdifferent voltage levels. As a result, both thick and thin oxidedielectric layers are required to accommodate the passage of high andlow voltages, respectively. For instance, thin oxide dielectric layers,capable if withstanding low voltages, are necessary to maintain highspeed operation of the device, and perform such functions as memorystorage, etc. However, the thin dielectric material is incapable ofsafely accommodating the higher voltages, as required to perform suchfunctions as capacitance decoupling, low to high and high to low signalinterfacing, electrostatic discharge protection, etc.

Accordingly, there is a need in the industry to efficiently construct asemiconductor device capable of safely accommodating both high and lowvoltages, while maintaining a small overall device size.

SUMMARY OF THE INVENTION

The first general aspect of the present invention provides electronicstructure comprising: a first device and a second device formed within asubstrate, wherein the first device includes a first dielectric and thesecond device includes a second dielectric, and wherein the seconddielectric has a greater thickness than the first dielectric.

The second general aspect of the present invention provides a method offorming an electronic structure, comprising: providing a substrate;forming a first device having a first dielectric thickness; and forminga second device having a second dielectric thickness, wherein the seconddielectric thickness is greater than the first dielectric thickness.

The foregoing and other features of the invention will be apparent fromthe following more particular description of the embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of this invention will be described in detail, withreference to the following figures, wherein like designations denotelike elements, and wherein:

FIG. 1 depicts a cross-sectional view of a wafer having a pad and a maskthereon in accordance with a first embodiment of the present invention;

FIG. 2 depicts the wafer of FIG. 1 following patterning of the mask andpad;

FIG. 3 depicts the wafer of FIG. 2 following the formation of a collarand buried plate;

FIG. 4 depicts the wafer of FIG. 3 following the deposition of a firstnode dielectric;

FIG. 5 depicts the wafer of FIG. 4 following the deposition of aconductive material;

FIG. 6 depicts the wafer of FIG. 5 following a partial removal of theconductive material;

FIG. 7 depicts the wafer of FIG. 6 following the deposition of a secondnode dielectric;

FIG. 8 depicts the wafer of FIG. 7 following a planarization process;

FIG. 9 depicts a transistor having a barrier layer and a conductivelayer in accordance with a second embodiment of the present invention;

FIG. 10 depicts the transistor of FIG. 9 having a mask thereon;

FIG. 11 depicts the transistor of FIG. 10 having a thin and thickdielectric layer formed thereon;

FIG. 12 depicts the transistor of FIG. 10 having a sacrificial oxidelayer formed thereon in accordance with a third embodiment;

FIG. 13 depicts a transistor having a hard mask and a photo resist maskthereon in accordance with a fourth embodiment of the present invention;

FIG. 14 depicts the transistor of FIG. 13 following patterning andetching of the hard mask;

FIG. 15 depicts the transistor of FIG. 14 having a barrier layer and aconductive layer thereon;

FIG. 16 depicts the transistor of FIG. 15 following planarization;

FIG. 17 depicts the transistor of FIG. 16 following removal of the hardmask;

FIG. 18 depicts a transistor having dielectric material implantedtherein in accordance with a fifth embodiment of the present invention;

FIG. 19 depicts the transistor of FIG. 18 having a conductive layerthereon;

FIG. 20 depicts the transistor of FIG. 19 having a thin and a thickdielectric layer formed thereon;

FIG. 21 depicts a transistor having dielectric layer deposited thereonin accordance with a sixth embodiment of the present invention;

FIG. 22 depicts a transistor having a conductive layer thereon inaccordance with a seventh embodiment of the present invention;

FIG. 23 depicts the transistor of FIG. 22 having a photo resist maskthereon;

FIG. 24 depicts the transistor of FIG. 23 having a thin and thickdielectric layer, and an oxidation enhanced diffusion region formedtherein;

FIG. 25 depicts the transistor of FIG. 23 having a sacrificial oxidelayer thereon;

FIG. 26 depicts a transistor in accordance with an eighth embodiment ofthe present invention;

FIG. 27 depicts a substrate in accordance with a ninth embodiment of thepresent invention;

FIG. 28 depicts the substrate of FIG. 27 having trenches formed therein;

FIG. 29 depicts the substrate of FIG. 28 having a barrier layer andconductive layer thereon;

FIG. 30 depicts the substrate of FIG. 29 having a photo resist layerthereon;

FIG. 31 depicts the substrate of FIG. 30 after etching;

FIG. 32 depicts the substrate of FIG. 31 having a photo resist maskthereon;

FIG. 33 depicts the substrate of FIG. 33 following oxidation;

FIG. 34 depicts the substrate of FIG. 32 having a sacrificial oxidelayer thereon;

FIG. 35 depicts the substrate of FIG. 28 having a conductive layerthereon in accordance with a tenth embodiment of the present invention;

FIG. 36 depicts the substrate of FIG. 35 having a photo resist maskthereon; and

FIG. 37 depicts the substrate of FIG. 36 following oxidation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although certain embodiments of the present invention will be shown anddescribed in detail, it should be understood that various changes andmodifications may be made without departing from the scope of theappended claims. The scope of the present invention will in no way belimited to the number of constituting components, the materials thereof,the shapes thereof, the relative arrangement thereof, etc. Although thedrawings are intended to illustrate the present invention, the drawingsare not necessarily drawn to scale.

Referring to the drawings, FIG. 1 shows a cross-sectional view of asubstrate 10 in accordance with a first embodiment. The substrate 10 maybe a silicon wafer of a dynamic random access memory (DRAM), an embeddeddynamic random access memory (EDRAM) device, or other similar device.The substrate 10 includes a pad 12 formed thereon. The pad 12 comprisessilicon nitride, or other similarly used material. The pad 12, depositedusing low pressure chemical vapor deposition (LPCVD), or other similarlyused techniques, has a thickness within the range of approximately50-300 nm, e.g., 100 nm. The pad 12 functions as a polish stop layerduring a subsequent process step (described infra).

The substrate 10 further includes a mask 14 over the pad 12. The mask 14may be a hard mask comprising silicon dioxide or other similar material.The mask 14 is formed having a thickness in the range of approximately100-2000 nm, e.g. 1000 nm.

A plurality of trenches are then patterned within the mask 14 and pad 12using conventional photolithographic techniques. In the present example,only two trench patterns 16 and 18 are shown in FIG. 2 for ease ofillustration. The trench patterns 16, 18, having different widths W1 andW2, respectively, are patterned on the surface of the substrate 10. Forexample, the first trench pattern 16 patterns an array trench capacitor,while the second trench pattern 18 patterns a support trench capacitor.

As shown in FIG. 3, the trench patterns 16, 18 are then used to formtrenches 20, 22 within the substrate 10. In particular, the trenches 20,22 are formed using a conventional reactive ion etch (RIE) process, orother similar process. The trenches 20, 22 are etched to a depth in therange of approximately 1-10 microns, e.g., 6-7 microns. As illustrated,the support trench 22, having a greater width W2 opening than the widthW1 opening of the array trench 20, etches to a greater depth than thearray trench 20. The support trench 22 is formed having a greater widthW2 opening, and therefore will etch to a greater depth, than that of thearray trench 20, for purposes of manufacture, and will be described inmore detail below.

Thereafter, a buried plate 24 and collar 26 are formed within each ofthe trenches 20, 22 using conventional techniques well known in the art(shown in FIG. 3). For example, as described in publication by T. Ruppet al., (IEDM Tech. Dig., p.33, 1999), which is herein incorporated byreference, the buried plate 24 and collar 26 may be formed by firstdepositing a silicon nitride barrier layer or film within the bottom ofthe trenches 20, 22. The trenches 20, 22 are filled with photoresist,which is then etched to a depth equal to that of the collar 26. Thesilicon nitride within the upper region of each trench is etched. Thephotoresist is removed from the remaining portion of each trench 20, 22.The upper region of each trench 20, 22 is then thermally oxidized,wherein the silicon nitride remaining within the lower regions of thetrenches 20, 22 serve as a mask. The SiN from the lower region of eachtrench 20, 22 are then removed, and thermal dopant diffusion is used toform a buried plate within each trench 20, 22. It should be noted thatother conventionally used techniques may also be used.

As illustrated in FIG. 4, a thin node dielectric material 28 is thenformed over the surface of the substrate 10, covering the pad 12 and thetrenches 20, 22. The thin node dielectric material 28 comprises siliconnitride, or other similar materials, such as, a combination of silicondioxide and nitride, re-oxidized silicon nitride, tantalum oxide,titanium oxides, etc. The thin node dielectric material 28 is depositedusing LPCVD techniques, and has a thickness in the range ofapproximately 2-10 nm, e.g., 3 nm. Alternatively, the thin nodedielectric material 28 may be formed using thermal oxidation of siliconor other reactive techniques, (e.g., nitridation of silicon).

A conductive material 30, such as amorphous silicon, polysilicon, orother similar material, such as TiN, W, or other refractory materials,is conformally deposited on the surface of the substrate 10, asillustrated in FIG. 5. The conductive material 30 is deposited usingconventional LPCVD, or other similar techniques. The conductive material30 is deposited such that the material 30 substantially fills the arraytrench 20, but only partially fills the support trench 22 andconformally covers the walls of the support trench 22. In particular,the conductive material 30 is deposited having a thickness more thantwice the width W1 of the array trench 20, and less than twice the widthW2 of the support trench 22.

The excess conductive material 30 on the surface of the substrate 10 andwithin the support trench 22 is removed using an isotropic partial etch,such as a Fl or Cl containing chemical dry etch, or other similarprocess. The conductive material 30 within the array trench 20, however,is not removed, and in fact forms a completed array capacitor 21, asillustrated in FIG. 6.

Thereafter, a thick node dielectric material 32 is formed over thesurface of the substrate covering the thin node dielectric material 28on the surface of the pad 12, as well as within the support trench 22(FIG. 7). In the alternative, the thin node dielectric material 28covering the surface of the pad 12 and within the support trench 22 maybe removed using a conventional etch process, such as hot phosphoricacid, or a solution containing Hf and glycerol, prior to the formationof the thick node dielectric material 32.

The thick node dielectric material 32 comprises silicon nitride,deposited or thermally grown silicon dioxide, or other similarmaterials, such as, a combination of silicon dioxide and nitride,re-oxidized silicon nitride, tantalum oxide, titanium oxides, etc. Forthe case of deposited thick node dielectric material 32, LPCVDtechniques may be used, with a thickness in the range of approximately2-10 nm, e.g., 5 nm.

A conductive material 34, such as amorphous silicon, polysilicon, orother similar material, is then deposited over the surface of thesubstrate 10 to substantially fill the support trench 22. The conductivematerial 34 is deposited using conventional LPCVD, or other similartechniques. Thereafter, the excess conductive material 34 on the surfaceof the substrate 10 is removed using planarization techniques, such as achemical mechanical planarization (CMP) technique (FIG. 8). Theplanarization also removes the thick node dielectric material 32 fromthe surface of the substrate 10, (as well as the thin node dielectricmaterial 28 if not already removed prior to the deposition of the thicknode dielectric material 32), and a portion of the pad 12, wherein thepad 12 serves as a polish stop layer. This forms the completed supportcapacitor 23.

The thick dielectric material 32 within the support capacitor 23 resultsin a lower capacitance per unit area within the support capacitor 23than within the array capacitor 21, which has thin dielectric material28. Furthermore, the support capacitor 23 has a higher “breakdownvoltage” than the array capacitor 21. In other words, the increaseddielectric thickness within the support capacitor 23 allows for exposureto higher voltages than those which the array capacitor 21 can safelywithstand, without producing failure. Therefore, the support capacitor23 may be used for decoupling, or other similar functions, that thearray capacitor 21 would not be capable of reliably performing.Moreover, the present invention provides support capacitors 23 capableof withstanding higher voltages than the array capacitors 21 (due to theincreased dielectric thickness of the support capacitors 23), with only20-50%, typically a 30%, increase in capacitor area, rather than the400% increase required using conventional solutions, in which thecapacitors are aligned in series.

Although the thick node dielectric 32 decreases the capacitance of thesupport capacitor 23, this reduction is off-set by the increased surfacearea within the support capacitor 23. In particular, the increased widthW2 of the support trenches 22 produces a deeper etched trench 22 due tothe reduction in aspect ratio of the support trench 23. This results inan increased surface area within the support capacitor 23, whichincreases the overall capacitance of the support capacitor 23, therebyoff-setting the reduction in capacitance per unit area, due to theincreased dielectric thickness, and gaining back the lost capacitance.This is desirable because it produces a device having more sustainablevoltage levels.

Additionally, by forming the support capacitor 23 having a greatertrench width W2 than that of the array capacitor 21, a “maskless”process may be used during the manufacture of the device. In otherwords, rather than using conventional masking techniques to form thedifferent trench capacitors 21, 23, the differences in trench 20, 22size are used to differentiate between the array capacitor 21 and thesupport capacitor 23 during formation. Particularly, because the supporttrench 22 is larger than the array trench 20, the support trench 22 isunder-filled, or only partially filled, during deposition of theconductive material 30 that fills the array trench 20. As a result, theconductive material within the support trench 22 may be easily removedwithout removing the conductive material within the array trench 20 thatforms the completed array capacitor 21.

In accordance with a second embodiment of the present invention, FIG. 9shows a cross-sectional view of a substrate 100, such as a singlecrystal silicon wafer of a MOSFET device. The substrate 100, in thisexample, a transistor, includes a shallow trench isolation (STI) 102formed therein using processes known in the art. A barrier layer 104 isdeposited over the surface of the substrate 100 using LPCVD, or othersimilar processes. The barrier layer 104 comprises a dielectric, such adeposited silicon nitride, a grown nitridized oxide, a grown ordeposited oxide, a deposited nitride, an oxidized nitride, etc. Thebarrier layer 104 is deposited having a thickness in the range ofapproximately 5-50 Å. The barrier layer 104 serves as an etch stop layerduring the removal of the conductive layer, and provides a high qualityinterface between the substrate 100 and the subsequent oxidized layer(described infra).

A cladding or conductive layer 106, such as a thin insitu dopedpoly-silicon, amorphous silicon, intrinsic poly-silicon, or othersimilarly used material, is deposited over the barrier layer 104. Theconductive layer 106 is deposited, using LPCVD techniques, or othersimilarly used processes, at a thickness in the range of approximately100-500 Å.

As illustrated in FIG. 10, a photo resist mask 108 is deposited andpatterned over the substrate 100. The mask 108 exposes a first region110 of the substrate 100 and covers a second region 112 of the substrate100, wherein a dotted line 114 indicates the separation between thefirst and second regions 110, 112. Thereafter, the conductive layer 106and the barrier layer 104 covering the substrate 100 within the firstregion 110 are removed, for example, using conventional patterning andetching techniques, to expose the surface of the substrate 100.

The photo resist mask 108 is then removed from the substrate 100, and aconventional oxidation process begins simultaneously within both regions110, 112. In particular, as shown in FIG. 11, a portion of the substrate100 is oxidized in the first region 110, forming a first thin dielectricor gate oxide layer 116. Similarly, the conductive layer 106 within thesecond region 112 is totally consumed during the oxidation process,forming a second thick dielectric or gate oxide layer 118. The barrierlayer 104 beneath the second dielectric layer 118 prevents “oxidationenhanced diffusion,” (OED) a phenomenon wherein dopant in the conductivematerial 106 diffuses into the substrate 100, and dopant diffusion inthe substrate 100 is enhanced.

The second dielectric layer 118 is thicker than the first dielectriclayer 116 because the oxidation rate within the material of theconductive layer 106, for instance, the poly-silicon, has asubstantially greater oxidation growth rate than that of the singlecrystal silicon material of the substrate 100. In particular, the ratioof growth rates is approximately 4:1 or 5:1 between these two materials.

Alternatively, in accordance with a third embodiment of the presentinvention, following the removal of the photo resist mask 108 in FIG. 10from the second region 112, a thin layer of sacrificial oxide 122 may begrown over both regions 110, 112 of the substrate 100 (FIG. 12). Forinstance, the sacrificial oxide 122 may be formed by oxidizing bothregions 110, 112 using a rapid thermal oxidation (RTO) process, at800-1000° C. for approximately 120 seconds. The sacrificial oxide 122 isthen removed from both regions 110, 112, using known techniques. Thesacrificial oxide 122 preconditions the surface of both regions 110,112, prior to forming the final dielectric layers 116, 118 in accordancewith the second embodiment, shown in FIG. 11.

In accordance with a fourth embodiment, prior to depositing a blanketcoating of the barrier layer 104, a hard mask 120 may be deposited overthe substrate 100, as illustrated in FIG. 13. The hard mask 120comprises silicon nitride or other similarly used material. Thereafter,the photo resist mask 108 is deposited over the hard mask 120. The hardmask 120 is then patterned and etched using known techniques, and thephoto resist mask 108 is removed, such that the hard mask 120 covers thefirst region 110 of the substrate 100 and exposes the second region 112of the substrate 100, as illustrated in FIG. 14.

Thereafter, the barrier layer 104 and the conductive layer 106 areconformally deposited over the surface of the substrate 100 and the hardmask 120, as described above and illustrated in FIG. 15. The conductivelayer 106 is planarized down to the barrier layer 104, using a CMP, orother similar process (FIG. 16). The exposed barrier layer 104 and hardmask 120 in the first region 110 are then removed, as shown in FIG. 17.Thereafter, the oxidation process begins as described above, resultingin the structure shown in FIG. 11.

As described in the third embodiment, following the removal of the hardmask 120 (FIG. 17), a sacrificial oxide layer 122 may be formed overboth regions 110, 112 (FIG. 12). The sacrificial oxide layer 122 isstripped, as described above. Thereafter, both regions 110, 112, areoxidized to form the dielectric layers 116, 118 illustrated in FIG. 11.

Alternatively, the structure may be formed according to the second,third and fourth embodiments without depositing a barrier layer 104.Therefore, in accordance with a fifth embodiment, a dielectric material107, such as nitrogen, may be pre-implanted into both the first and thesecond regions 110, 112 of the substrate 100 (FIG. 18). Thereafter, theconductive layer 106 is formed over the second region 112, (FIG. 19),using either the photo resist mask 108 or the hard mask 120 techniquesdescribed above. The oxidation process is performed simultaneously inboth regions 110, 112 to form the first and second dielectric layers116, 118, respectively, as shown in FIG. 20.

The pre-implantation serves the dual purpose of reducing the oxidationrate of the substrate 100 material in the first region 110, andhindering the diffusion of dopant from the conductive layer 106 materialinto the substrate 100 in the second region 112. As a result, thedifference in thickness of the oxidized dielectric between the firstregion 110 and the second region 112 would be further enhanced orexaggerated.

In accordance with a sixth embodiment, a thin layer of dielectricmaterial 109 may be formed over the entire surface of the substrate 100(FIG. 21). For example, nitridized oxide may be grown on the surface ofthe substrate 100, or a thin nitride layer, having a thickness ofapproximately 1-20 Å, may be deposited over the substrate 100, usingknown techniques. Thereafter, the conductive layer 106 is formed overthe second region 112 of the substrate 100 using either the photo resistmask 108 or hard mask 120 techniques. The oxidation process is performedsimultaneously in both regions 110, 112 to form the first and seconddielectric layers 116, 118, respectively, as shown in FIG. 20. The thinlayer of dielectric material 109 functions in a similar manner as thatof the pre-implantation of dielectric material 107.

In accordance with a seventh embodiment of the present invention, adevice may be formed without the use of the barrier layer 104,pre-implantation of the dielectric material 107, or the thin layer ofdielectric material 109. As illustrated in FIG. 22, the conductive layer106 is deposited over the surface of the substrate 100 as describedabove. The photo resist mask 108 is placed over the substrate 100, suchthat the first region 110 is exposed and the second region 112 iscovered. The conductive layer 106 in the first region 110 is removed, asillustrated in FIG. 23. Thereafter, both regions 110, 112 are oxidizedas described above. In this instance, however, not only are thedielectric layers 116, 118 formed, but as illustrated in FIG. 24, anadditional OED region 124, or oxidation enhanced diffusion region, formsbeneath the dielectric layer 118 in the second region 112. In otherwords, because the barrier layer 104, or other dielectric material 107,109, is not deposited between the substrate 100 and the conductive layer106, dopant from the conductive layer 106 and/or a portion of theconductive layer 106 diffuses into the substrate 100 during theoxidation processing, and diffusion of the dopant in the substrate 100is enhanced.

As described in the third embodiment above, the sacrificial oxide layer122 may be formed over both regions 110, 112 following the removal ofthe photo resist mask 108 (FIG. 25). The sacrificial oxide layer 122 isstripped, as described above. Thereafter, both regions 110, 112, areoxidized to form the dielectric layers 116, 118, and the OED region 124,illustrated in FIG. 24.

In a similar manner to that of the fourth embodiment, and in accordancewith an eighth embodiment, the hard mask 120 may be deposited over thesubstrate 100. The photo resist mask 108 is placed over the hard mask120 (FIG. 13), and the hard mask 120 is patterned and etched such thatthe first region 110 is covered and the second region 112 is exposed,(FIG. 14). The conductive layer 106 is then deposited over the surfaceof the hard mask 120 and the substrate 100, and planarized using a CMPprocess, leaving the structure illustrated in FIG. 26. Thereafter, thehard mask 120 is removed, and the first and second regions 110, 112 areoxidized to form dielectric layers 116, 118, and OED region 124 (FIG.24).

As described above in third embodiment, a sacrificial oxide layer 122may be formed over both regions 110, 112 following the removal of thehard mask 120 (FIG. 25). The sacrificial oxide layer 122 is stripped, asdescribed above. Thereafter, both regions 110, 112, are oxidized to formthe dielectric layers 116, 118, and the OED region 124 illustrated inFIG. 24.

In accordance with a ninth embodiment, FIG. 27 shows the substrate 100having the STI 102 formed therein. A pad oxide layer 130 is formed orthermally grown over the surface of the substrate 100. The pad oxidelayer 130 comprises a thermally grown oxide, or a deposited oxidematerial, having a thickness of approximately 25-75 Å. A pad nitridelayer 132 is deposited, using conventional techniques, over the padoxide layer 130, having a thickness of approximately 300-1000 Å. A padTEOS (tetraethylorthosilicate) layer 134 is deposited over the padnitride layer 132, having a thickness of approximately two times thethickness of the pad nitride layer 132, e.g., approximately 600-2000 Å.Thereafter, a layer of photo resist 136 is deposited, using conventionaltechniques, over the pad TEOS layer 134, having a thickness ofapproximate to the thickness of the pad oxide layer 130, the pad nitridelayer 132 and the pad TEOS layer 134, e.g., approximately 1000-4000 Å.

The layer of photo resist 136 is then exposed, using conventionalmasking techniques. The pad oxide layer 130, the pad nitride layer 132,the pad TEOS layer 134, and the substrate 100 are etched to form a firsttrench 138 and a second trench 140 within the substrate 100. Unlike thefirst embodiment, the first and second trenches may be formed havingdimensions that are substantially similar. Thereafter, the layer ofphoto resist 136 is removed using conventional techniques, asillustrated in FIG. 28.

As illustrated in FIG. 29, the barrier layer 104 is conformallydeposited over the surface of the substrate 100 and within the trenches138, 140. Thereafter, the conductive layer 106 is deposited over thesurface of the substrate 100 and within the trenches 138, 140. A secondlayer of photo resist 142 is deposited over the surface of the substrate100, filling the trenches 138, 140 (FIG. 30).

Using an O₂ plasma etch, or other similar process, the layer of photoresist 142 is etched down to approximately the depth of the pad oxidelayer 130, as illustrated in FIG. 31. Thereafter, the conductive layer106, the barrier layer 104, the pad TEOS layer 134 and the pad nitridelayer 132 are removed from the surface of the substrate 100 down to thepad oxide layer 130. A photo resist mask 108 is patterned over thesubstrate 100, wherein the first region 110 is exposed and the secondregion 112 is covered (FIG. 32). The conductive layer 106 and thebarrier layer 104 within the first trench 138 are removed using aconventional etching process.

The photo resist mask 108 is then removed, and the layer of photo resist142 remaining in the second trench 140 is removed using a conventionaletch process. The first and second regions 110, 112 are simultaneouslyoxidized, as described above, to form a thin dielectric layer 116 withinthe first trench 138 and a thick dielectric layer 118 within the secondtrench 140, as illustrated in FIG. 33.

As illustrated in FIG. 34, and described in the third embodiment,following the removal of the photo resist mask 108 and the photo resistlayer 142 within the second trench 140 (FIG. 32), a sacrificial oxidelayer 122 may be formed within the trenches 138, 140 of both regions110, 112 (FIG. 34). The sacrificial oxide layer 122 is then stripped, asdescribed above. Thereafter, both regions 110, 112, are oxidized to formthe dielectric layers 116, 118 illustrated in FIG. 33.

In accordance with a tenth embodiment, the conductive layer 106 may bedeposited within the trenches (FIG. 35) following formation of the firstand second trenches 138, 140 (FIG. 28), rather than depositing thebarrier layer 104. Thereafter, the layer of photo resist 142 isdeposited, and the conductive layer 106, the pad TEOS layer 134 and thepad nitride layer 132 are etched down to the pad oxide layer 130 (FIG.36). The photo resist mask 108 is placed over the substrate 100 coveringthe second region 112, and the photo resist layer 142 within the firsttrench 138 is removed. Thereafter, both regions 110, 112 aresimultaneously oxidized to form the thin dielectric layer 116, the thickdielectric layer 118 and the OED region 124 (FIG. 37).

Similar to the description above, the dielectric material 107, such asnitrogen, may be pre-implanted into both the first and the secondregions 110, 112 of the substrate 100 prior to depositing the conductivelayer 106. Also, the thin layer of dielectric material 109 may be formedover the entire surface of the substrate 100 prior to depositing theconductive layer 106.

While this invention has been described in conjunction with the specificembodiments outlined above, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, the embodiments of the invention as set forth aboveare intended to be illustrative, not limiting. Various changes may bemade without departing from the spirit and scope of the invention asdefined in the following claims.

We claim:
 1. A method of forming first and second electronic devicescomprising: forming a first trench capacitor in a substrate, having afirst surface dimension; forming a second trench capacitor in saidsubstrate, having a second surface dimension, wherein the second surfacedimension is greater than the first surface dimension; depositing afirst dielectric having the first dielectric thickness within at leastthe first trench; depositing a first material within the first andsecond trenches, wherein the first material substantially fills thefirst trench, and at least partially fills the second trench; removingthe first material from the second trench; forming a second dielectrichaving the second dielectric thickness within the second trench; anddepositing a second material within the second trench.
 2. The method ofclaim 1, wherein the substrate comprises a semiconductor wafer.
 3. Themethod of claim 1, wherein the first and second materials are a materialselected from the group consisting of: amorphous silicon andpolysilicon.
 4. The method of claim 1, wherein removing the firstmaterial from the second trench comprises isotropically etching thefirst material within the second trench.
 5. A method of forming firstand second capacitors on a substrate, comprising the steps of: etchingfirst and second trenches in the substrate through a single mask;forming a first capacitor in a first trench disposed in a first regionof the substrate, said first capacitor having a given breakdown voltageand a first node dielectric; and forming a second capacitor in a secondtrench disposed in a second region of the substrate, said secondcapacitor having a breakdown voltage greater than said first capacitorand a second node dielectric different from said first node dielectric.6. The method of claim 5, wherein said step of etching said first andsecond trenches in said substrate comprises the steps of: forming a masklayer over the substrate, said mask having a first opening of a firstwidth and a second opening of a width greater than said first width; andetching areas of the substrate exposed by the mask to form trenches,wherein a second trench formed in an area of the substrate beneath saidsecond opening has a depth greater than a first trench formed in an areaof the substrate beneath said first opening.
 7. The method of claim 6,wherein a first capacitor is formed in said first trench and a secondcapacitor is formed in said second trench, said second capacitor havingless capacitance per unit area than said first capacitor and having agreater total capacitance area than said first capacitor.
 8. The methodof claim 5, wherein an array capacitor is formed in said first trenchand a decoupling capacitor is formed in said second trench.
 9. Themethod of claim 5, wherein said first node dielectric is thinner thansaid second node dielectric.